Implementation of structured metal packing for the design of biofilm reactor : analysis by high energy X-ray tomography and application to the production of lipopeptides by Bacillus subtilis

Poster (2012, October 08)

1. Whereas multi-species biofilm reactors are commonly used for treatments of water and gas effluents, new strategies are arising for the development of mono-species biofilm reactors in order to produce ... [more ▼]

1. Whereas multi-species biofilm reactors are commonly used for treatments of water and gas effluents, new strategies are arising for the development of mono-species biofilm reactors in order to produce high added value molecules. Thus, it is required to design new bioreactors able to promote the growth of the biomass on the form of a biofilm and to identify the key physico-chemical parameters involved in order to optimize the bioprocess. 2. Aim of this study was to investigate a pilot-scale biofilm reactor comprising a metal structured packing promoting growth of Bacillus subtilis as a biofilm for the production of lipopeptides, high added value compounds with high surface active properties. 3. In this work, the mechanical stirring system of a 20L stirred tank bioreactor has been removed and replaced by a metal structured packing positioned in the headspace of the vessel above a liquid phase. The culture medium is continuously recirculated on the packing thanks to a peristaltic pump and air supply is performed just above the liquid phase under the packing. High energy X-ray tomography was used to estimate non-invasively the biofilm distribution inside the packing and permitted to define parameters that affect scale-up. Performances of the biofilm reactor were compared with a submerged culture in a stirred tank reactor in terms of lipopeptides production. 4. After 72 hours of fermentation, 94 % of the total biomass adheres onto the metal packing on the form of a biofilm. The colonization of this latter has been visualized non-invasively by X-ray tomography directly inside the packing and shows a conical repartition of the biofilm mass (about 25% of the total volume of the packing) as well as the presence of clogging. However, unlike the submerged culture, no foam formation appeared during fermentation and surfactin yield reaches 345,4 ± 32,8 mg / L for the biofilm reactor against 277,3 ± 34,4 mg / L in the stirred tank reactor. 5. In conclusion, this experimental setting leads to a major technological progress avoiding foam formation and increasing surfactin production. Nevertheless, significant improvements are required at the level of the biofilm distribution in thin layers inside the packing in order to increase mass transfer and lipopeptides recoveries. Further investigations will be devoted to the optimization of the physico-chemical parameters involved in biofilm distribution. [less ▲]

Implementation of the finite element method for non-lambertian indoor surfaces

in Proceedings of the 7th "Lux Europa" congress (Edinburgh 1993) - Volume 2 (1993)

Implementation of the harmonic balance FEM method for large-scale saturated electromagnetic devices

in Software for Electrical Engineering - Analysis and Design IV (1999)

Implementation of the Walloon agri-environmental measures "strip of wildflowers" and "strip of arable plants":scientific support

Poster (2007, November)

Implementing BSL II & BSL III activities in an existing facility : the case of the Animal facility of the CHU at University of Liège, Belgium "

(2006, May 10)

Implementing pedagogic strategies between vets and farmers to create synergies in udder health management: Project Mammipack®

Poster (2009, December)

Udder health is usually considered as a health and economic problem for farmers. We now consider that mastitis is the result of many factors related to the environment, the pathogen and the host. What may ... [more ▼]

Udder health is usually considered as a health and economic problem for farmers. We now consider that mastitis is the result of many factors related to the environment, the pathogen and the host. What may have been forgotten in the process is the fact that nowadays, the main interface with mastitis is the farmer, and their knowledge about mastitis is very heterogeneous. This reflexion has led to the creation of a technical and pedagogical pack called “Mammipack” which contains different tools, from all actors of the dairy chain. We included small charts explaining the most important risk factors identified through epidemiology, good dairy practices and its effect on milk flow, milking machine check-up, how-to for mastitis milk sample, a how-to for performance records use for udder health management, a resume on genetic selection of sires and mastitis, charts upon nutrition factors and their main effect on udder physiology during lactation and dry-off, resume on veterinary drugs good management in the farm. Small laminated sheets upon milk sampling for bacteriology and teats evaluation were also joined in order to be use in parlors, sterile sampling tubes were also given in the pack. A mastitis record pad was designed to record the main clinical forms and the treatment chosen. Eventually, the book Udder Health® was added to have a complete modern look on that problem in dairy farms. 25 farmers were selected on a voluntary base by 12 veterinarians, and they answered to questionnaires about their main practices regarding herd structure, mastitis treatment, and southern Belgium main 19 risk factors. They had to answer basic questions concerning udder health on 15 points. They agreed to keep a record of all next mastitis cases in their farms and take milk samples for bacteriology each time at day 0 and day 21 during 3 months. The main objective is to show to a group of dairy farmers that mastitis could take several different forms from one farm to another, in term of incidence, pathogens and clinical forms. One other purpose is to show the difficulty to have bacteriological cure, even when physical cure has happened. After all, one collateral objective was to create the Mammipack®, designed for farmers and vets to increase their ability to collaborate on mastitis management through most dairy chain actors’ expertise. [less ▲]

Implementing quantum algorithms in hyperfine levels of ultracold polar molecules by optimal control

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13

Implementing the Bianco and Yohai estimator for logistic regression

in Computational Statistics & Data Analysis (2003), 44(1-2), 273-295

A fast and stable algorithm to compute a highly robust estimator for the logistic regression model is proposed. A criterium. for the existence of this estimator at finite samples is derived and the ... [more ▼]

A fast and stable algorithm to compute a highly robust estimator for the logistic regression model is proposed. A criterium. for the existence of this estimator at finite samples is derived and the problem of the selection of an appropriate loss function is discussed. It is shown that the loss function can be chosen such that the robust estimator exists if and only if the maximum likelihood estimator exists. The advantages of using a weighted version of this estimator are also considered. Simulations and an example give further support for the good performance of the implemented estimators. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

Implication de l'ergonomie cognitive en ingénierie de conception : la plate-forme créative du LUCID-ULg

Scientific conference (2011, November 09)

Implication de la compétition pour les acides aminés dans le contrôle biologique de la pourriture bleue des pommes en post-récolte

Conference (2008, April)